let wm = new WeakMap();

class Fish {
    constructor(name) {
        wm.set(this,{
            _fishbone:['草鱼','鲫鱼','青鱼']
        });

        this.name = name;


    }
    isBone() {
        return wm.get(this)._fishbone.includes(this.name);
    }
} 

let fish1 = new Fish('草鱼');
let fish2 = new Fish('茴鱼');

fish1.isBone();
fish2.isBone();
